A new snapshot of U.S. birth trends has just been released. It shows shifts in which women are having babies and how those infants are entering the world.

America’s birth and fertility rates (search) both rose by 2 percent in 2003, says the report. The birth rate reached 14.1 births per 1,000 people, up from 13.9 in 2002. The fertility rate (the number of births per 1,000 women aged 15-44 years) reached 66 births per 1,000 women.

Moms Are Older

It’s official: More women are having babies later in life. Most women still have babies in their 20s, but the numbers are shifting a bit. The birth rate rose for women aged 25-44 years and dropped 3 percent for teens and women in their early to mid-20s.

In fact, the birth rate for women aged 30 to 44 hasn’t been this high in 30 years, says the report.

Births rose 4 percent among women in their early to mid-30s, 6 percent for women in their late 30s, and 5 percent for women in their early to mid-40s. That brings their rates to about 95, 44, and 9 births per 1,000 people, respectively.

Meanwhile, teenage births dropped, as they have for more than a decade. Births for women in their mid- to late teens fell 3 percent since 2002, for a birth rate of about 42 births per 1,000 women.

More unmarried women also gave birth in 2003. The 4 percent increase brought their birth rate to almost 45 births per 1,000 unmarried women.

Less Smoking, More Prenatal Care

Two healthy trends are still going strong: More women aren’t smoking while pregnant and more are getting early prenatal care (search). Those patterns started about 15 years ago and continued in 2003.

The proportion of pregnant women who smoked dropped to 11 percent, down 4 percent from the previous year. Back in 1989, when birth certificates started noting maternal smoking, nearly one in five pregnant women smoked (19.5 percent).

More pregnant women are also getting prenatal care in their first trimester. The 2003 percentage was 84.1 percent, up from 83.7 percent a year earlier.

More Twins, Fewer Triplets

Actress Julia Roberts (search) has lots of company as a new mother of twins.

In 2003 -- a year before Roberts had her babies -- the twin birth rate (search) rose 3 percent, accounting for 31 out of every thousand births. That’s 38 percent higher than in 1990 and 65 percent higher than in 1980. The steepest rise in twin births has been in the oldest moms, the report shows.

However, the number of triplets and other multiple births fell slightly. The surge in those births over the last 20 years might be over, says the report.

C-Sections Hit Record High

Cesarean sections (search) (C-sections) have never been more common. Nearly 28 percent of all births in 2003 were done by C-section, an increase of 6 percent since 2002.

About half a million babies were born prematurely (before 37 weeks of gestation). That’s 12.3 percent of all births, slightly higher than 12 percent in 2002.

The percentage of low-birth-weight babies was 7.9 percent in 2003. That’s barely higher than 7.8 percent a year earlier. But since 1984, the percentage has risen by 18 percent.

Infant mortality also increased slightly in 2003. The infant mortality rate reached seven deaths per thousand live births in 2002. That’s up from 6.8 per 1,000 live births in 2001.

The numbers appear in the March issue of Pediatrics, which has tracked U.S. birth trends since 1959. The report was compiled by researchers including the CDC’s Joyce Martin, MPH.

The same study also showed record life expectancy of 77.3 years and declines in heart disease, cancer, and stroke. The CDC reported similar numbers earlier this week.

By Miranda Hitti reviewed by Brunilda Nazario, MD

SOURCES: Martin, J. Pediatrics, March 2005; vol 115: pp 619-634. News release, American Academy of Pediatrics. WebMD Medical News: “U.S. Life Expectancy Best Ever, Says CDC.”